Display device

ABSTRACT

A display device according to the present invention comprises a display panel, a housing sealing around the display panel and making a display screen of the display panel viewable from outside, and a heat exchanger collecting heat, which is arranged on a rear surface side of the display panel. Another display device according to the present invention comprises a housing having a waterproof structure and provided with an accommodation room formed therein, a display panel arranged in the accommodation room and including a display screen viewable from a front surface side of the housing, a heat exchanger collecting heat generated from the display panel and arranged on a rear surface side of the display panel, and a second heat exchanger releasing heat collected by the heat exchanger to outside of the housing and arranged outside the accommodation room.

The application Number 2008-255678, upon which this patent applicationis based, is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to display devices, and particularly to adisplay device for outside installation.

2. Description of Related Art

Conventionally, as a monitor for image display, often used areflat-panel displays such as a liquid crystal display. Most of theconventional liquid crystal displays are designed assuming that they areinstalled indoors, and the measures to protect the liquid crystaldisplay against weather, dust or the like are not taken. Thus, it hasbeen difficult to permanently install the conventional liquid crystaldisplay outdoors.

However, in recent years it is desired that a liquid crystal display ispermanently installed outdoors. The reason includes the fact that theliquid crystal display has a small thickness and that the resolution ofthe image is high. The small thickness allows the installation of thedisplay on the outer wall of the building or in narrow places such as abus stop. In addition, the high resolution allows an image to bedisplayed clearly even if the display screen is small.

Therefore, thought is an attempt to arrange a liquid crystal display,particularly an image display panel which is easy to be damaged byweather and dust among liquid crystal displays, in the inside of anaccommodation room that has a waterproof structure in order to protectthe liquid crystal display from weather and dust.

However, since there is no escape of heat from the inside of theaccommodation room to the outside when the image display panel isarranged in the inside of the accommodation room and it is waterproofed,the image display panel cannot be air-cooled naturally. Thus, a blackoutoccurs. The blackout is a phenomenon in which the temperature of theimage display panel rises due to the heat generated from an imagedisplay panel in operation or the sun light, and an original function ofthe liquid crystal falls to disable the image display.

It can be thought to provide cooling means to the liquid crystal displayto cool the image display panel, but there is a problem that a liquidcrystal display increases in size.

SUMMARY OF THE INVENTION

A first display device according to the present invention comprises adisplay panel, a housing sealing around the display panel and making adisplay screen of the display panel viewable from outside, and a heatexchanger collecting heat, and the heat exchanger is arranged on a rearsurface side of the display panel.

A second display device according to the present invention is the firstdisplay device, wherein the heat exchanger includes an evaporator and acondenser, and the evaporator is arranged at a position on the rearsurface side of the display panel and adjacent to a lower end surface ofthe display panel, while the condenser is arranged at a position belowthe display panel.

A third display device according to the present invention comprises ahousing having a waterproof structure and provided with an accommodationroom formed therein, a display panel arranged in the accommodation roomand including a display screen viewable from a front surface side of thehousing, a heat exchanger collecting heat generated from the displaypanel and arranged on the rear surface side of the display panel, and asecond heat exchanger releasing heat collected by the heat exchanger tooutside of the housing and arranged outside the accommodation room.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an image display system in which adisplay device is installed;

FIG. 2 is an exploded perspective view of the image display system;

FIG. 3 is a perspective view showing a usage example of the imagedisplay system;

FIG. 4 is a cross-sectional view taken along a line IV-IV shown in FIG.2;

FIG. 5 is a cross-sectional view taken along a line V-V shown in FIG. 4;

FIG. 6 is a cross-sectional view taken along a line VI-VI shown in FIG.4;

FIG. 7 is a cross-sectional view taken along a line VII-VII shown inFIG. 4;

FIG. 8 is a plain view of the image display system;

FIG. 9 is an enlarged view of a IX area shown in FIG. 5;

FIG. 10 is a perspective view taken along a line X-X shown in FIG. 4without showing a part;

FIG. 11 is a perspective view taken along a line XI-XI shown in FIG. 4without showing a part;

FIG. 12 is a cross-sectional view taken along a line XI-XI shown in FIG.4;

FIG. 13 is an enlarged view of a XIII area shown in FIG. 12;

FIG. 14 is an enlarged view of a XIV area shown in FIG. 12;

FIG. 15 is a perspective view of a rear surface wall forming anaccommodation room seen from below on a rear surface side;

FIG. 16 is a perspective view of the rear surface wall seen from aboveon a rear surface side;

FIG. 17 is an exploded perspective view of a heat releasing fin; and

FIG. 18 is a perspective view of a second heat releasing part formingthe heat releasing fin.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An image display system in which a display device of a preferredembodiment of the present invention is installed is discussed in detailbelow with reference to drawings.

1. General Description of Image Display System

An image display system has a flat rectangular solid-shaped appearanceas shown in FIG. 1, and comprises an image display device 1, a base 2, abackboard 3, a cover 4, a lighting apparatus 5 and a ventilation plate 6as shown in FIG. 2.

The image display device 1 is a device displaying a video on a frontsurface 101 of the image display system, and includes a liquid crystaldisplay 10 as shown in FIG. 5. More details of the image display device1 are described in “2. IMAGE DISPLAY DEVICE”.

On the base 2, formed is a frame member 21 for attaching the imagedisplay device 1 and the backboard 3, and the frame member 21 has astructure in which the image display device 1 and the backboard 3 can befitted therein.

The backboard 3 is an installation base for affixing an advertisingmaterial, and is placed in the frame member 21 on a rear surface side ofthe image display device 1. The advertising material is affixed to afront surface 31 of the backboard 3, namely a surface facing a rearsurface 102 side of the image display system.

Here, the backboard 3 is formed of a light transmitting material, inorder to transmit light emitted from the lighting apparatus 5. Also, theadvertising material affixed to the backboard 3 is formed of a lighttransmitting material in order to transmit the light emitted from thelighting apparatus 5. The advertising material formed of the lighttransmitting material is hereinafter referred to as an advertising film.

The cover 4 is attached to the base 2, and covers the front surface 31of the backboard 3 to which the advertising material is affixed. Theadvertising material is thereby protected by the cover 4.

Also, a part of the cover 4 opposed to the front surface of thebackboard 3 is formed of a light transmitting material. It is thuspossible to view the advertising material from the rear surface 102 sideof the image display system.

The lighting apparatus 5 is an apparatus for illuminating theadvertising film affixed to the front surface 31 of the backboard 3, andcomprises a plurality of fluorescent lamps extending in a generallyvertical direction. The lighting apparatus 5 is attached to the framemember 21 of the base 2 at a position between the image display device 1and the backboard 3. Details of arrangement of the lighting apparatus 5are described in “3. ARRANGEMENT OF LIGHTING APPARATUS”.

By illuminating the advertising film by the lighting apparatus 5, it ispossible to view letters or the like printed on the advertising filmeven at night.

The ventilation plate 6 is arranged on each of the front surface 101 andthe rear surface 102 of the image display system at a position below theimage display device 1. In the ventilation plate 6, defined are aplurality of ventilation holes 61 via which the inside and the outsideof the image display system communicate with each other.

The image display system described above is placed at a bus stop, forexample, as shown in FIG. 3. In such a case, the image display system isplaced so that the front surface 101 faces the inside of the bus stopand the rear surface 102 faces the outside of the bus stop.

It is thereby possible to provide various information to a user waitingin a bus stop with a still image or a moving image, and provide variousinformation to a person passing outside the bus stop. It is alsopossible to easily update the information displayed on the front surface101 by the image display device 1 by remote-controlling the imagedisplay system in a wired or wireless manner. Further, it is possible tocollectively manage the image display systems placed in a plurality ofbus stops.

Since the front surface 101 of the image display system faces the insideof the bus stop according to the installed condition of the imagedisplay system described above, it is hard for a driver of a car or thelike passing near the bus stop to see the front surface 101. Therefore,even when a moving image is displayed on the front surface 101, theattention of the driver is hard to be attracted to the moving image.

2. Image Display Device

The image display device 1 includes the liquid crystal display 10, ahousing 12, a plurality of heat pipes 13, circulation fans 18, heatreleasing fins 14, ventilation fans 15, 16 and a heat collecting fins 17as shown in FIGS. 4 and 5. As shown in FIG. 11, the image display device1 further includes an air conditioning machine 19, circulation fans 181and a heat insulation member 7.

2-1. Liquid Crystal Display

The liquid crystal display 10 is a flat-panel display, and includes animage display panel 11 and a circuit board lie for controlling the imagedisplay panel 11 as shown in FIG. 5. The image display panel 11 isarranged inside an accommodation room 121 to be discussed later, whilethe circuit board lie is arranged on an outer surface of a rear surfacewall 125 forming the accommodation room 121.

The image display panel 11 may take various shapes depending on theintended use. In this embodiment, the image display panel 11 takes alengthwise rectangular shape so that the image display system can beinstalled in a narrow place such as a bus stop. Also, a part of theimage display panel 11 adjacent to a display screen 112 in particular iseasy to generate heat and be heated to a high temperature.

2-2. Housing

(Accommodation Room)

The housing 12 has a waterproof structure, and is provided with theaccommodation room 121 formed therein as shown in FIG. 4. The imagedisplay panel 11 is arranged inside the accommodation room 121 with thedisplay screen 112 facing the front surface 101 of the image displaysystem as shown in FIG. 12.

In particular, the housing 12 includes a front surface wall 124 locatedon the display screen 112 side of the image display panel 11, a rearsurface wall 125 located on a rear surface 111 side of the image displaypanel 11, and side surface walls 121 a, 121 b located on the oppositesides of the image display panel 11. Also, the frame member 21 of thebase 2 has an upper end part located on an upper end surface 113 side ofthe image display panel 11 and a lower end part located on a lower endsurface 114 side of the image display panel 11.

The accommodation room 121 is formed by the front surface wall 124, therear surface wall 125, the side surface walls 121 a, 121 b, and theupper end part and the lower end part of the frame member 21, and ismaintained in a sealed or substantially sealed state.

Thus, by arranging the image display panel 11 inside the accommodationroom 121 maintained in the sealed or substantially sealed state, it ispossible to protect the image display panel 11 from weather and dusteven when the image display device 1 is installed outdoors.

The rear surface wall 125 is arranged at a position between the imagedisplay panel 11 and the backboard 3.

A part of the front surface wall 124 opposed to the display screen 112of the image display panel 11 is formed by a light transmittingmaterial, a glass material in particular, and the front surface wall 124forms not only the accommodation room 121 but also the front surface 101of the image display system. It is thus possible to view the displayscreen 112 of the image display panel 11 from the front surface side ofthe housing 12, i.e. the front surface 101 side of the image displaysystem.

(Circulation Flow Path)

Inside the accommodation room 121, formed is a circulation flow path 92surrounding the image display panel 11 as shown in FIGS. 11 and 12.Illustration of the heat pipe and the heat collecting fins 17 areomitted in order to show the circulation flow path 92 clearly in FIGS.11 and 12 and also in FIGS. 13 and 14 to be discussed later.

In this embodiment, the circulation flow path 92 comprises four flowpath portions 11 a to 11 d. The flow path portion 11 a is definedbetween the front surface wall 124 forming the accommodation room 121and the display screen 112 of the image display panel 11, and extendsalong the display screen 112 in the generally vertical direction. Theflow path portion 11 b is defined between the upper end part of theframe member 21 forming the frame 2 and the upper end surface 113 of theimage display panel 11. The flow path portion 11 c is defined betweenthe rear surface wall 125 forming the accommodation room 121 and therear surface 111 of the image display panel 11, and extends along therear surface 111 in the generally vertical direction. The flow pathportion 11 d is defined between the lower end part of the frame member21 and the lower end surface 114 of the image display panel 11.

The flow path portions 11 a to 11 d are connected to each other in thisorder circumferentially around the image display panel 11 to surroundthe image display panel 11. In other words, the upper end parts of theflow path portion 11 a and the flow path portion 11 c communicate witheach other via the flow path portion 11 b, and the lower end parts ofthe flow path portion 11 a and the flow path portion 11 c communicatewith each other via the flow path portion 11 d.

The air in the circulation flow path 92 is circulated around the imagedisplay panel 11 by the circulation fans 18, 181 as to be discussedlater. Therefore, the heat generated in a part adjacent to the displayscreen 112 of the image display panel 11 moves to the rear surface 111side of the image display panel 11 through the medium of the air in thecirculation flow path 92.

(Ventilation Path)

Inside the housing 12, defined is ventilation paths 122, 123 leading tothe outside of the housing 12 at positions outside the accommodationroom 121. In particular, as shown in FIG. 4, the ventilation path 122extends in the generally vertical direction along one of the sidesurface walls 121 a forming the accommodation room 121, and theventilation path 123 extends along the other side surface wall 121 bforming the accommodation room 121.

Thus, by defining the ventilation paths 122, 123 on both sides of theaccommodation room 121, it is possible to avoid an increase in size inthe thickness direction of the image display device 1.

An upper end part 122 a of the ventilation path 122 bends in a crankshape as shown in FIG. 6, and leads to the outside of the housing 12through a ventilation hole 62 (cf. FIG. 8) provided on an upper surface21 a of the frame member 21 of the base 2. It is similar about an upperend part 123 a of the ventilation path 123.

As shown in FIG. 7, a lower end part 122 b of the ventilation path 122leads to the outside of the housing 12 through the ventilation hole 61of the ventilation plate 6 placed below the image display device 1.

2-3. Heat Pipe

A plurality of heat pipes 13 are arranged in the flow path portion 11 cof the circulation flow path 92. In particular, the plurality of heatpipes 13 is fixed to the rear surface 111 of the image display panel 11being repeatedly arranged at a predetermined interval in the generallyvertical direction as shown in FIG. 4. In this embodiment, one set ofthe heat pipes 13 arranged in such a manner is provided on either sideof a centerline 111 a of the rear surface 111.

As shown in FIG. 9, the heat pipe 13 arranged on the ventilation path122 side of the centerline 111 a passes through one of the side surfacewalls 121 a forming the accommodation room 121 to extend from the insideof the accommodation room 121 to the inside of the ventilation path 122.In particular, the heat pipe 13 extends from the rear surface 111 of theimage display panel 11 towards the ventilation path 122, and passesthrough the one of the side surface walls 121 a to project into theinside of the ventilation path 122.

Here, on the side surface wall 121 a forming the accommodation room 121,defined is a through-hole through which each of the heat pipes 13passes. The through-hole is sealed by silicon rubber or the like withthe heat pipe 13 passing therethrough. The inside of the accommodationroom 121 is thereby maintained in the sealed state.

The heat pipe 13 arranged on the ventilation path 123 side of thecenterline 111 a passes through the other side surface wall 121 bforming the accommodation room 121 to extend from the inside of theaccommodation room 121 into the inside of the ventilation path 123 in asimilar manner to the heat pipe 13 extending into the ventilation path122 (cf. FIG. 5).

By using the heat pipes 13 described above, the heat generated from theimage display panel 11 can be collected in the inside of theaccommodation room 121. In other words, the heat can be collected fromthe air flowing through the circulation flow path 92 by the heat pipes13, and the heat of the image display panel 11 can be collected directlyfrom the rear surface 111 by the heat pipes 13. The collected heat isled to the outside of the accommodation room 121 by the heat pipes 13 tobe released to the inside of the ventilation paths 122, 123. In otherwords, each heat pipes 13 functions as heat exchange means included inthe image display device 1.

The heat released from the heat pipes 13 to the inside of theventilation paths 122, 123 is released to the outside of the housing 12through the ventilation paths 122, 123. Therefore, the temperatureincrease of the image display panel 11 is restrained. As a result, thefunction of the liquid crystal display 10 is maintained in a preferablestate.

Since, in this embodiment, the heat pipes 13 are arranged in repetitionon the rear surface 111 of the image display panel 11 at thepredetermined interval, it is possible to collect the heat from thewhole flow path portion 11 c of the circulation flow path 92 and fromthe whole rear surface 111 of the image display panel 11. Coolingefficiency of the image display device 1 thereby becomes higher.

Since a refrigerant (water or the like) for heat exchange is filled inthe inside of each heat pipe 13, it is preferable to arrange each of theheat pipes 13 diagonally as shown in FIG. 4 from a point of view ofincreasing the heat exchange efficiency of the heat pipe 13. Thediagonally arranged heat pipes 13 extend from the inside of theaccommodation room 121 to the inside of the ventilation paths 122, 123obliquely upward.

A part (a low temperature part) of each heat pipe 13 located inside theventilation paths 122, 123 is thereby at a higher place than a part (ahigh temperature part) located inside the accommodation room 121 in thegenerally vertical direction. Therefore, the refrigerant in the heatpipe 13 is evaporated in the high temperature part, to rise toward thelow temperature part, and then, liquefied in the low temperature part toflow down towards the high temperature part, and it is evaporated in thehigh temperature part again.

Thus, by arranging the heat pipe 13 diagonally, the refrigerantcirculates through the heat pipe 13 efficiently, and the heat exchangeefficiency of the heat pipe 13 increases.

Further, in this embodiment, since the heat pipes 13 are arranged on therear surface 111 of the image display panel 11, it is possible to avoidlimit on the display screen 112 due to the arrangement of the heat pipe13, e.g., a reduction in size of the display screen 112 or the increasein size of the image display device 1.

For further description of arrangement of the heat pipes 13, each of theheat pipes 13 described above is arranged along the rear surface 111 ofthe image display panel 11 from a point of view of increasing collectingefficiency of the heat from the rear surface 111 of the image displaypanel 11.

In this embodiment, a step is formed on the rear surface 111 of theimage display panel 11 as shown in FIGS. 5 and 10 due to a relationbetween a mounting location of the image display panel 11 and mountinglocations of electronic parts and the circuit board lie mounted on theimage display device 1. Each of the heat pipes 13 is bent in a crankshape in the step part so that the heat pipe 13 follows the shape of therear surface 111 of the image display panel 11.

It is thereby possible to reduce wasted space produced due to deploymentof the heat pipe 13. Also, contact area with the rear surface 111 of theimage display panel 11 increases. As a result, the heat exchangeefficiency between the heat pipe 13 and the image display panel 11increases.

Further, in this embodiment, each of the heat pipes 13 is arranged inrepetition at the predetermined interval in the generally verticaldirection as shown in FIG. 4, and extends to the inside of theventilation paths 122, 123 while keeping a distance with the adjacentheat pipe 13 at a predetermined interval. Thus, the heat pipes 13 arearranged in repetition at a predetermined interval in the generallyvertical direction also in the inside of the ventilation paths 122, 123.

Therefore, the heat collected by the heat pipes 13 can be releaseddispersedly in the inside of the ventilation paths 122, 123. As aresult, the heat exchange (heat dissipation) efficiency of the heatpipes 13 in the inside of the ventilation paths 122, 123 increases.

2-4. Air Conditioning Machine

The air conditioning machine 19 comprises an evaporator 191 and acondenser 192 which are heat exchangers as shown in FIG. 2 and FIGS. 10to 12. Heat is collected by the evaporator 191, and the collected heatcan be released by the condenser 192.

The evaporator 191 is arranged in the inside of the accommodation room121 at a position on the rear surface 111 side of the image displaypanel 11 and adjacent to the lower end surface 114 of the image displaypanel 11 as shown in FIGS. 11 and 12. In other words, the evaporator 191is arranged in the lower end part of the flow path portion 11 c of thecirculation flow path 92. Thus, it is possible to avoid the increase insize of the image display device 1 in the height direction by arrangingthe evaporator 191 on the rear surface 111 side of the image displaypanel 11.

Also, the circulation flow path 92 can be shortened by arranging theevaporator 191 on the rear surface 111 side, rather than the lower endsurface 114 side, of the image display panel 11.

As shown in FIGS. 11 and 12, the condenser 192 is arranged at a positioninside the housing 12 and outside the accommodation room 121. Inparticular, the condenser 192 is arranged at a position below theaccommodation room 121, i.e., a position below the image display panel11. The condenser 192 is arranged opposed to the ventilation plate 6.

Since the heat exchange efficiency is high in both the evaporator 191and the condenser 192 in the air conditioning machine 19 describedabove, heat can be efficiently collected from the air flowing in thecirculation flow path 92 by the evaporator 191, and efficiently releasedby the condenser 192 to the outside of the housing 12 via the pluralityof ventilation holes 61 provided to the ventilation plate 6. Therefore,the heat generated from the image display panel 11 is collected by theair conditioning machine 19, and the temperature increase of the imagedisplay panel 11 is inhibited. As a result, the function of the imagedisplay panel 11 is maintained in a preferable state.

Thus, the air conditioning machine 19 functions as the heat exchangerincluded in the image display device 1.

In this embodiment, the air conditioning machine 19 is used as the heatexchanger collecting heat from the air in the circulation flow path 92,but another heat exchanger may be adopted instead of the airconditioning machine 19.

Also, the air conditioning machine 19 may comprise a compressor alongwith the evaporator 191 and the condenser 192.

Preferably, the compressor is arranged at a position below the displaypanel 11, in particular, a position below the accommodation room 121.

In such a structure of the air conditioning machine 19, the air whichcirculates through the circulation flow path 92 and flowed into the airconditioning machine 19 is cooled by the evaporator 191, while therefrigerant in the evaporator 191 is evaporated by the heat from theair. The evaporated refrigerant is compressed by the compressor to be ina condition of the elevated temperature and pressure, and then flowsinto the condenser 192. In the condenser 192, the refrigerant of theelevated temperature and pressure is cooled to generate a liquidrefrigerant at low temperature. And then, the liquid refrigerant flowsinto the evaporator 191 again to cool the air in the circulation flowpath 92.

2-5. Circulation Fan

The circulation fans 18, 181 are fans for circulating the air in thecirculation flow path 92 along the circulation flow path 92. As shown inFIGS. 11 and 12, the circulation fans 18 are arranged at a position onthe rear surface 111 side of the image display panel 11 and adjacent tothe upper end surface 113 of the image display panel 11. In other words,the circulation fans 18 are arranged in the upper end part of the flowpath portion 11 c of the circulation flow path 92.

The circulation fans 18 make the air in the flow path portion 11 c ofthe circulation flow path 92 flow downward as shown in FIG. 13.

The circulation fans 181 are arranged in the inside of the accommodationroom 121 on the rear surface 111 side of the image display panel 11 andadjacent to the evaporator 191. In this embodiment, as shown in FIGS. 11and 12, the circulation fans 181 are arranged at positions in the lowerend part of the flow path portion 11 c of the circulation flow path 92and above the evaporator 191.

The circulation fan 181 sends wind toward the evaporator 191 as shown inFIG. 14. The circulation fan 181 has a function to draw the air from theupper part of the circulation flow path 92.

As shown in FIGS. 13 and 14, the air in the circulation flow path 92thereby circulates around the image display panel 11 in a direction ofthe solid line arrows.

In other words, by driving the circulation fans 18, 181, the air in theflow path portion 11 a along the display screen 112 of the image displaypanel 11 flows from bottom to top in the generally vertical directionand passes through the flow path portion 11 b along the upper endsurface 113 of the image display panel 11 to flow into the path portion11 c along the rear surface 111 as shown in FIG. 13. The air whichflowed into the flow path portion 11 c flows from top to bottom alongthe flow path portion 11 c and passes through the flow path portion 11 dalong the lower end surface 114 of the image display panel 11 to returnto the flow path portion 11 a as shown in FIG. 14.

By using the circulation fans 18, 181 described above, the air in theflow path portion 11 a along the display screen 112 of the image displaypanel 11 can be led to the flow path portion 11 c along the rear surface111 efficiently. Therefore, the heat generated in a part adjacent to thedisplay screen 112 of the image display panel 11 is collected by theheat pipes 13 arranged in the rear surface 111 side of the image displaypanel 11 and the evaporator 191 efficiently. In other words, by usingthe air in the circulation flow path 92, it is possible to air-cool theimage display panel 11, in particular, the display screen 112 of theimage display panel 11.

Therefore, temperature increase of the image display panel 11 isrestrained, and as a result, the function of the image display panel 11is maintained in a preferable state.

When it is taken into account that the image display panel 11 isair-cooled by the circulation fans 18, 181, the heat pipes 13 and theevaporator 191, it can be understood that a cooling mechanism is formedby the circulation fans 18, 181, the heat pipe 13 s and the evaporator191.

In this embodiment, since wind is sent toward the evaporator 191 by thecirculation fan 181 (cf. FIG. 14), the air in the circulation flow path92 can be sent into the evaporator 191 without stagnation in the flowpath portion 11 c. Therefore, the heat can be collected by theevaporator 191 efficiently.

Also, in this embodiment, since the circulation fans 18, 181 arearranged in the upper end part and the lower end of the flow pathportion 11 c respectively, the air is easy to flow along the circulationflow path 92, and the flow speed increases. Therefore, the image displaypanel 11 can be cooled uniformly, and as a result, it does not happenthat only a part of the image display panel 11 adjacent to theevaporator 191 is cooled.

However, if the speed of the air flowing through the circulation flowpath 92 increases excessively, the heat exchange efficiency in theevaporator 191 decreases. Therefore, in this embodiment, it ispreferable that ten circulation fans 18 are arranged in the upper endpart of the flow path portion 11 c as shown in FIG. 4, while threecirculation fans 181 are arranged in the lower end part of the flow pathportion 11 c as shown in FIGS. 15 and 16.

Further, in this embodiment, the air in the flow path portion 11 a alongthe display screen 112 of the image display panel 11 flows from bottomto top in the generally vertical direction. Therefore, also due to aproperty of the air of rising when warmed by heat, the air in the flowpath portion 11 a flows from bottom to top efficiently.

Therefore, the air is easy to circulate along the circulation flow path92, and the heat generated in a part adjacent to the display screen 112of the image display panel 11 can be led to the heat pipes 13 and theevaporator 191 efficiently. As a result, the heat exchange (heatcollection) efficiency in the heat pipes 13 and the evaporator 191increases, thereby increasing the cooling efficiency of the imagedisplay device 1.

Further, in this embodiment, the air in the circulation flow path 92 canbe circulated efficiently since the circulation fans 18 are arranged inthe upper end part of the flow path portion 11 c of the circulation flowpath 92, namely at a position adjacent to the flow path portion 11 balong the upper end surface 113 of the image display panel 11. Thereason is described below.

In a part of the circulation flow path 92 where the circulation flowpath 92 is widened, a path resistance decreases. In particular, thecirculation flow path 92 is narrow in the flow path portion 11 b and iswidened at the entrance to the flow path portion 11 c from the flow pathportion 11 b as shown in FIG. 13. Thus, the air in the flow path portion11 b is easy to be led to the flow path portion 11 c.

Therefore, by arranging the circulation fans 18 in the upper end part ofthe flow path portion 11 c, the air in the flow path portion 11 b can beled to the flow path portion 11 c efficiently. As a result, the air inthe circulation flow path 92 circulates efficiently.

In the case where the circulation flow path 92 is widened at theentrance to the flow path portion 11 b from the flow path portion 11 a,the circulation fans 18 may be arranged at or in the vicinity of aposition where the air flows out from the flow path portion 11 a for thesame reason as above.

As mentioned earlier, since the circulation fans 18, 181 are arranged inthe rear surface 111 side of the image display panel 11, it is possibleto avoid an increase in size of the image display device 1 in the heightdirection.

In this embodiment, the circulation fans 18, 181 are used as thecirculating means for circulating the air in the circulation flow path92, but another circulating means may be employed instead of thecirculation fans 18, 181.

2-6. Heat Releasing Fin

The heat releasing fin 14 is arranged in the inside of the ventilationpath 122 as shown in FIG. 9, and is connected to a projecting part 131of the heat pipe 13 projecting to the inside of the ventilation path122. In this embodiment, the heat releasing fin 14 is formed ofaluminum.

In particular, each of the heat releasing fins 14 comprises a first heatreleasing part 141 and a second heat releasing part 142 sandwiching theprojecting part 131 of the heat pipe 13 from both sides. The first heatreleasing part 141 includes a base part 141 a and a fin part 141 bcoupled with the base part 141 a perpendicularly, and is arranged on afront surface of the housing 12 side of the projecting part 131 of theheat pipe 13.

The second heat releasing part 142 includes a base part 142 a and a finpart 142 b coupled with the base part 142 a perpendicularly, and isarranged on a rear surface side of the housing 12 side of the projectingpart 131 of the heat pipe 13.

In the base parts 141 a and 142 a of the first heat releasing part 141and the second heat releasing part 142, defined is a pair of grooves 141c, 142 c as shown in FIGS. 17 and 18. The projecting part 131 of theheat pipe 13 fits in the pair of grooves 141 c, 142 c when theprojecting part 131 is sandwiched by the first heat releasing part 141and the second heat releasing part 142 from both sides.

More specifically, the pair of grooves 141 c, 142 c is formed in theshape of a semicylinder, and when the projecting part 131 of the heatpipe 13 is sandwiched from both sides by the first heat releasing part141 and the second heat releasing part 142, a cylindrical hole is formedby the pair of grooves 141 c, 142 c, and the projecting part 131 of theheat pipe 13 fits in the cylindrical hole.

In this embodiment, the plurality of heat pipes 13 are arranged on therear surface 111 of the image display panel 11 in line in the generallyvertical direction (cf. FIG. 4), and the plurality of heat releasingfins 14 corresponding to the plurality of heat pipes 13 are arrangedinside the ventilation path 122 in the generally vertical direction.

As shown in FIGS. 17 and 18, a plurality of first heat releasing parts141 corresponding to the plurality of heat pipes 13 are formedintegrally, and a plurality of second heat releasing parts 142corresponding to the plurality of heat pipes 13 are also formedintegrally.

In a similar manner to the heat releasing fins 14 arranged inside theventilation path 122 described above, the heat releasing fins 14 arearranged in the inside the ventilation path 123 also (cf. for example,FIG. 4).

By using the heat releasing fins 14 described above, the heatdissipation efficiencies from the heat pipes 13 to the inside of theventilation paths 122, 123 increase, resulting in the increase in thecooling efficiency of the image display device 1.

In this embodiment, each of the heat releasing fins 14 comprises thefirst heat releasing part 141 and the second heat releasing part 142,and the pair of grooves 141 c, 142 c is formed in the first heatreleasing part 141 and second heat releasing part 142. And therefore, bysimply sandwiching the heat pipe 13 from both sides by the first heatreleasing part 141 and the second heat releasing part 142 to make theheat pipe 13 fitted in the pair of grooves 141 c, 142 c, it is possibleto connect the heat releasing fins 14 to the heat pipe 13 while formingthe heat releasing fins 14. Therefore, it is easy to connect the heatreleasing fins 14 to the heat pipe 13.

In this embodiment, the plurality of first heat releasing parts 141corresponding to the plurality of heat pipes 13 are formed integrally,and the plurality of second heat releasing parts 142 corresponding tothe plurality of the heat pipes 13 are also formed integrally.Therefore, it is possible to attach the heat releasing fin 14 to all theplurality of heat pipes 13 each by performing one operation ofsandwiching the plurality of heat pipes 13 with the first heat releasingparts 141 and the second heat releasing parts 142. As a result,installation of the heat releasing fins 14 to the plurality of heatpipes 13 is simplified.

In this embodiment, in each first heat releasing part 141, a pluralityof fin parts 141 b are coupled with the base part 141 a perpendicularlyas shown in FIG. 17, and a gap is defined between the fin parts 141 b.This is similar in each second heat releasing part 142. The air flowingthrough the ventilation paths 122, 123 flows through the gap describedabove.

In FIG. 17, tips of the plurality of fin parts 141 b are coupled witheach other by a coupling part in each first heat releasing part 141, andthe gap mentioned above is surrounded by the fin part 141 b, the basepart 141 a and the coupling part. This is similar in each second heatreleasing part 142. In such a case, it is possible to use the heatreleasing fins 14 as duct fins which function also as ducts by makingthe air in the ventilation paths 122, 123 pass through only the saidgap. Of course the air in the ventilation paths 122, 123 may pass boththrough the gap and outside the gap.

In this embodiment, the heat releasing fin 14 is used as a heatreleasing member for increasing the heat dissipation efficiency from theheat pipe 13 to the inside of the ventilation paths 122, 123, however,another heat releasing member may be employed instead of the heatreleasing fin 14.

2-7. Ventilation Fan

The ventilation fans 15, 16 are arranged in the inside of theventilation path 122 as shown in FIG. 4, and the ventilation fan 15 isarranged in the upper end part 122 a of the ventilation path 122, whilethe ventilation fan 16 is arranged in the lower end part 122 b of theventilation path 122.

The ventilation fans 15, 16 make the air in the ventilation path 122flow along the ventilation path 122 in the same direction. Inparticular, the ventilation fan 15 exhausts the air in the ventilationpath 122 via the ventilation hole 62 to the outside of the housing 12 asshown in FIG. 6, thereby making the air in the ventilation path 122 flowfrom bottom to top in the generally vertical direction. The ventilationfan 16 inhales the air outside the housing 12 via the ventilation hole61 to the inside of the ventilation path 122 as shown in FIG. 7, therebymaking the air in the ventilation path 122 flow from bottom to top inthe generally vertical direction. In FIGS. 6 and 7, a flow of the air isindicated by solid line arrows.

In the inside of the ventilation path 123 also, the ventilation fans 15,16 are arranged in a similar manner to the ventilation path 122 (cf.FIG. 4), and the ventilation fans 15, 16 make the air in the ventilationpath 123 flow from bottom to top in the generally vertical direction.

By using the ventilation fans 15, 16 described above, the heat releasedto the inside of the ventilation paths 122, 123 from the heat pipes 13can be dissipated to the outside of the housing 12 efficiently.Therefore, in the ventilation paths 122, 123, the heat dissipationefficiencies of the heat pipes 13 and the heat releasing fins 14increase.

In this embodiment, the air in the ventilation paths 122, 123 flows frombottom to top, and therefore, also due to a property of the air ofrising when warmed, the air in the ventilation paths 122, 123 warmed bythe heat released to the inside of the ventilation paths 122, 123 flowsfrom bottom to top efficiently. Therefore, the heat released within theventilation paths 122, 123 can be dissipated to the outside of thehousing 12 efficiently.

In this embodiment, the ventilation fans 15, 16 are used as fan means toexhaust the air in the ventilation paths 122, 123 to the outside of thehousing 12, however, another fan means may be employed instead of theventilation fans 15, 16.

2-8. Heat Collecting Fin

Each of the heat collecting fins 17 is connected to the plurality ofheat pipes 13 in the inside of the accommodation room 121 as shown inFIG. 4. In particular, each of the heat collecting fins 17 comprises abase part 171 and a fin part 172 as shown in FIG. 9. The base part 171extends over the plurality of heat pipes 13, and comes into contact withthe plurality of heat pipes 13. The fin part 172 is coupledperpendicularly to the surface of the base part 171, and extends fromone end of the base part 171 to the other end of the base part 171 inthe longitudinal direction.

By using the heat collecting fins 17 described above, it is possible toefficiently collect the heat released from the image display panel 11 tothe inside of the circulation flow path 92 and lead it to the heat pipes13. A function of each heat pipe 13 as the heat exchanger is therebyenhanced, resulting in the increase in the cooling efficiency of theimage display device 1.

In FIG. 4, the heat collecting fins 17 are connected only to the heatpipes 13 on the ventilation path 122 side of the centerline 111 a.However, in reality, the heat collecting fins 17 are connected also tothe heat pipes 13 on the ventilation path 123 side similarly.

In this embodiment, the heat collecting fin 17 is used as the heatcollecting member for collecting heat from the air flowing through thecirculation flow path 92, however, another heat collecting member may beemployed instead of the heat collecting fin 17.

2-9. Heat Insulation Member

The heat insulation member 7 is interposed between the evaporator 191and the image display panel 11 as shown in FIG. 14. In particular, theevaporator 191 is arranged in the rear surface 111 side of the imagedisplay panel 11, and the heat insulation member 7 is arranged betweenthe rear surface 111 of the image display panel 11 and a front surface191 a of the evaporator 191. Urethane or silicon-based rubber is used,for example, for a material of the heat insulation member 7.

As mentioned earlier, the heat generated in the image display panel 11is led to the evaporator 191 through the medium of the air flowing inthe circulation flow path 92 and is collected by the evaporator 191. Byusing the heat insulation member 7 described above, it is possible toprevent a part of the image display panel 11 adjacent to the evaporator191 from being cooled excessively in a process of collecting heat by theevaporator 191. Therefore, a temperature distribution of the imagedisplay panel 11 becomes uniform, resulting in maintaining the functionof the image display panel 11 in a preferable state.

3. Arrangement of Lighting Apparatus

The rear surface wall 125 forming the accommodation room 121 includes avertical wall part 125 a and inclined wall parts 125 b, 125 c as shownin FIG. 12. The vertical wall part 125 a extends along the rear surface111 of the image display panel 11. The inclined wall part 125 b bendstoward the backboard 3 from the upper end of the vertical wall part 125a and extends in the obliquely upward direction, while the inclined wallpart 125 c bends toward the backboard 3 from the lower end of thevertical wall part 125 a and extends in the obliquely downwarddirection.

First accommodation spaces 12 b, 12 c along the front surfaces of theinclined wall parts 125 b, 125 c respectively are thereby definedbetween the rear surface wall 125 and the rear surface 111 of the imagedisplay panel 11. In other words, the first accommodation spaces 12 b,12 c are defined in the upper end part and the lower end part of theflow path portion 11 c of the circulation flow path 92 respectively.

Also, a second accommodation space 12 a along the rear surface of thevertical wall part 125 a is defined between the rear surface wall 125and the backboard 3.

The circulation fan 18 is arranged in one of the first accommodationspaces 12 b as shown in FIGS. 12 and 13, while the circulation fan 181and the evaporator 191 are arranged in the other first accommodationspace 12 c as shown in FIGS. 12 and 14.

Also, the lighting apparatus 5 for illuminating the advertising film isarranged in the second accommodation space 12 a as shown in FIG. 12. Inparticular, a plurality of fluorescent lamps forming the lightingapparatus 5 are arranged in line horizontally along the vertical wallpart 125 a in the inside of the second accommodation space 12 a.

By providing the inclined wall parts 125 b, 125 c on the rear surfacewall 125 forming the accommodation room 121 as mentioned earlier, thefirst accommodation spaces 12 b, 12 c where the circulation fans 18, 181and the evaporator 191 are arranged are defined inside the accommodationroom 121, and the second accommodation space 12 a where the lightingapparatus 5 are arranged is defined outside of the accommodation room121 at a position generally below the circulation fans 18, and generallyabove the circulation fans 181 and the evaporator 191. In other words,the second accommodation space 12 a is interposed between the firstaccommodation spaces 12 b, 12 c in the vertical direction or in thegenerally vertical direction.

Therefore, it is possible to arrange the circulation fans 18, 181, theevaporator 191 and the lighting apparatus 5 in the vertical direction orgenerally vertical direction, and as a result, it is possible to avoidthe increase in size of the image display device 1 in the thicknessdirection.

4. Modification

4-1. Modification 1

In the image display device 1 described above, the plurality of heatpipes 13 are arranged in repetition at the predetermined interval in thegenerally vertical direction (cf. FIG. 4), however, this is not thelimitation and there may be another embodiment. For example, the heatpipes 13 may be arranged at different interval.

However, it is preferable that the heat pipes 13 are arranged throughthe whole rear surface 111 of the image display panel 11 in a similarmanner to the image display device 1 described above from a point ofview of increasing the cooling efficiency of the image display device 1.The heat can be thereby collected from the whole rear surface 111 of theimage display panel 11.

4-2. Modification 2

In the image display device 1 described above, the ventilation fans 15,16 make the air in the ventilation paths 122, 123 flow from bottom totop, however, they may make the air flow from top to bottom. Forexample, in consideration of environment or the like of the installationlocation of the image display system provided with the image displaydevice 1, the air in the ventilation paths 122, 123 better flows fromtop to bottom in some cases.

Also, in the image display device 1 described above, two ventilationfans are provided to each of the ventilation paths 122, 123, however,the number of ventilation fans to be provided to the ventilation paths122, 123 may be one or may be three or more.

Further, in the image display device 1 described above, the ventilationfans 15 are arranged in the upper end parts 122 a, 123 a of theventilation paths 122, 123, and the ventilation fans 16 are arranged inthe lower end parts 122 b 123 b of the ventilation paths 122, 123,however, they may be arranged in other positions, not limited to thesepositions. However, it is necessary to arrange them so that the air inthe ventilation paths 122, 123 can be exhausted to the outside of thehousing 12.

4-3. Modification 3

In the image display device 1 described above, the circulation flow path92 comprises the flow path portion 11 a along the display screen 112,the flow path portion 11 b along the upper end surface 113, the flowpath portion 11 c along the rear surface 111, and the flow path portion11 d along the lower end face 114. However, another course surroundingthe image display panel 11 in the inside of the accommodation room 121may be used as the circulation flow path 92.

For example, flow path portions may be defined between the side surfaceof the image display panel 11 and the side surface walls 121 a, 121 bforming the accommodation room 121 respectively, to define thecirculation flow path 92 by said flow path portions and the flow pathportions 11 a, 11 c.

Also, the image display device 1 described above, the circulation fans18 make the air in the flow path portion 11 a along the display screen112 flow from bottom to top, however, the circulation fans 18 may makethe air flow from top to bottom. In such a case, it is preferable toinstall the circulation fan 18 in the position adjacent to the lower endsurface 114 of the image display panel 11. The position of thecirculation fans 18 is not limited to the position adjacent to the upperend surface 113 or the lower end surface 114 of the image display panel11, and may be another position.

4-4. Modification 4

In the image display device 1 described above, the circulation fans 181are arranged in the position above the evaporator 191 in the lower endpart of the flow path portion 11 c of the circulation flow path 92,however, the circulation fans 181 may be arranged in the position belowthe evaporator 191.

Since the circulation fans 181 take in the air from the evaporator 191according to such an embodiment, the air is sent into the evaporator 191from above. Therefore, the heat can be collected by the evaporator 191efficiently.

4-5. Modification 5

In the image display device 1 described above, the heat releasing fins14 arranged inside the ventilation path 122 is formed by the first heatreleasing part 141 and the second heat releasing part 142, and theprojecting part 131 of the heat pipe 13 is sandwiched from both sides bythe first heat releasing part 141 and the second heat releasing part 142with the projecting part 131 fitted in the pair of grooves 141 c, 142 c.However, it is also possible that, for example, each heat releasing fin14 is formed only by the first heat releasing part 141, and the heatreleasing fin 14 is attached to the projecting part 131 of the heat pipe13 by fitting the projecting part 131 of the heat pipe 13 in the groove141 c defined in the first heat releasing part 141.

According to such an embodiment, installation of the heat releasing fins14 to the heat pipe 13 can be simplified.

The present invention is not limited to the foregoing embodiment inconstruction but can be modified variously within the technical scopeset forth in the appended claims. For example, as well as the liquidcrystal display, the technique can be applied in an image display devicewhich includes the flat-panel display such as a plasma display or anorganic electroluminescence (Electro-Luminescence) display.

Also, in the above described embodiment, the circulation fans 18 areprovided in order to circulate the air around the image display panel11, however, the present invention is not limited to this. For example,the fans 18 may be provided in order to form a flow of the air only onthe display screen 112 of the image display panel 11. In such a case,the air drawn into the fans 18 is exhausted to the outside, for example,from the upper part of the image display device 1.

1. A display device comprising: a display panel; a housing sealingaround the display panel and making a display screen of the displaypanel viewable from outside; a heat exchanger collecting heat, whichincludes an evaporator and a condenser, and a circulation fan, whereinthe evaporator is arranged at a position on a rear surface side of thedisplay panel and adjacent a lower end surface of the display panel, thecondenser is arranged at a position below the display panel, and thecirculation fan is arranged to circulate air along a flowpath within thehousing and around the display panel.
 2. A display device comprising: ahousing having a waterproof structure and provided with an accommodationroom formed therein; a display panel arranged in the accommodation roomand including a display screen viewable from a front surface side of thehousing, the accommodation room and display panel arranged to describean air flow circulation path within the housing and around the displaypanel; a heat exchanger collecting heat generated from the display paneland arranged on a rear surface side of the display panel; and a secondheat exchanger releasing heat collected by the heat exchanger to outsideof the housing and arranged outside the accommodation room.